1. Field of the Invention
This invention relates to the field of firearms. More specifically, the invention relates to articles of manufacture for use as identifiers of objects using infrared light. In exemplary embodiments, the invention finds use in targeting and sight calibration for firearms equipped with infrared sighting scopes. The present invention thus generally relates to signage visible to those using infrared imaging techniques, and particularly to a method of calibrating infrared weapons sights.
2. Description of Related Art
Users of infrared cameras for operations such as the military and police have the advantage of being able to view heat sources, such as people, in complete darkness. However, they are unable while using infrared imaging techniques to differentiate words or symbols. In order to convey information they can utilize heated objects, such as exothermic chemical heaters. However, these and similar technologies only create a point in the imaging system. Therefore, the ability to convey complex information is very limited. The invention addresses this and demonstrates a method of making more complex signage that is visible to people using infrared imaging.
In particular, users of weapons with infrared sights such as the TWS (Thermal Weapon Sight) from BAE, DRS Technologies, or Raytheon must calibrate their sight to their weapon to ensure they will hit their target. This is very important whenever the sight is disturbed in any way. Using traditional iron sights, the user fires at the center of a target similar to the target shown in FIG. 1. The group of shots should land a predefined distance away from the target center depending on the weapon and sight characteristics. If the shots do not hit the target where expected, the sights must be adjusted so they will hit the target where they should. However, the soldier using a thermal weapon sight is unable to see the target to perform this calibration. Migliorini (U.S. Pat. No. 6,337,475) proposes using a small electrically heated silhouette placed on the front of a standard 25 meter zeroing target. This appears to be a valid solution, but lacks in the following:                a battery is required for operation, which poses logistical problems due to the greater weight of the 25 meter zeroing target. Additionally, battery disposal can create logistical problems;        the addition of a battery and wiring poses significant cost increases in the 25 meter zeroing target relative to those used with iron sights; and        the heat from the silhouette can bleed off from it and begin to warm the target, thereby increasing the size of the target for the user. This could result in lower accuracy.        
Others have also proposed articles of manufacture, methods, and means for sighting of infrared optical devices. Among these are U.S. Pat. No. 6,767,015, which discloses a thermal target; U.S. Pat. No. 6,051,840, which discloses an infrared heat emitting device; U.S. Pat. No. 6,020,040, which discloses a thermal pack having a plurality of individual heat cells; and U.S. Pat. No. 5,918,590, which discloses heat cells.
Although each of these solutions has advantages, each also has drawbacks and limitations. Therefore a new method of creating signage is required that will address needs in the art.